Very compact wide-angle zoom lens system

ABSTRACT

A very compact wide-angle zoom lens system with favorably corrected aberrations comprising a first lens group consisting of a negative meniscus lens element and a lens component having negative refractive power, a second lens group consisting of a positive cemented lens component and a negative meniscus lens element, and a third lens group comprising at least a positive meniscus lens element and a cemented lens component. The lens system is so designed as to permit zooming by displacing said first, second and third lens groups respectively.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a zoom lens system and morespecifically to a compact wide-angle zoom lens system.

(B) Description of the Prior Art

Remarkable progress has recently been made in wide-angle zoom lenssystems. However, it has conventionally been considered very difficultto design wide angle zoom lens systems very compactly. The reason for itis that diameter of the front lens element is unavoidably increased, incase of zoom lens systems, in order to utilize oblique rays reaching thecorners of image plane, and diameter of filter is determined accordingto diameter of the front lens element. Even if it is possible tominimize diameter of the front lens element, diameter of filter isincreased as angle of field is widened and, therefore, outside diameterof the lens systems as completed products is still enlarged. Further,when focusing is to be preformed by the front lens group, diameter ofthe lens systems as completed products must be still increased takingthe advancing distance for focusing into consideration so that theoblique rays will not be eclipsed. Zoom lens systems have an inherentfactor to have large dimensions since airspaces are required fordisplacing lens groups for zooming.

SUMMARY OF THE INVENTION

A general object of the present invention is to provide a compactwide-angle zoom lens system wherein a lens group having a negative focallength is arranged on the object side and aberrations are favorablycorrected though it has a very wide field angle of 84° at its wideposition.

There have conventionally been known to those skilled in the artinverted telephoto type zoom lens systems consisting of two lens groups.As field angle is widened, however, it abruptly becomes difficult tocorrect spherical aberration, coma, curvature of field, etc. over entirevariable range of focal length in such lens systems. As a method tosolve this problem, it can be considered to enhance flexibility forcorrecting aberrations by increasing number of lens groups or lenselements to be displaced for zooming. Although this method is possibletheoretically, it is not preferable in practice since it poses manyproblems related to mechanisms and precision of lens systems ascompleted products.

The present invention has been achieved by positively applying theconcept of minimization for wide-angle lens systems for generalphotographic cameras (general wide-angle lens systems other than zoomlens systems). Speaking in other words, the lens system according to thepresent invention comprises two fundamental negative and positive lensgroups, the positive one of which is divided into two groups to beslightly displaced relative to each other for zooming, thereby enhancingflexibility for correcting aberrations. Composition of the zoom lenssystem according to the present invention is illustrated in FIG. 1through FIG. 4. Speaking concretely, the lens system according to thepresent invention comprises a negative meniscus lens element having aconvex surface on the object side and a positive and negative lenselement which are cemented or separated, a second lens group consistingof a positive cemented lens component and a negative meniscus singlelens element having a convex surface on the object side, and a thirdlens group comprising at least a positive meniscus single lens elementhaving a convex surface on the object side and a cemented lenscomponent. Said zoom lens system is characterized in that said first,second and third lens groups are displaced independently for zooming andthat said lens system satisfy the conditions enumerated hereunder:

    1.5f<|f.sub.1 |<2f, f.sub.1 <0           (1)

    12f<f.sub.2 <15f                                           (2)

    0.55f<D.sub.2 <f                                           (3)

wherein the reference symbols represent as defined below:

f: focal length of the lens system as a whole at its wide position.

f₁ : focal length of the first lens group

f₂ : focal length of the second lens group

D₂ : total length of the second lens group (d₆ +d₇ +d₈ +d₉)

The first lens group of the lens system according to the presentinvention has such a composition as is often seen in general wide-anglezoom lens systems but is characterized in that it has a short focallength f₁ as defined in the condition (1), thereby making it possible todesign a compact wide-angle zoom lens system. If f₁ is shorter than thelower limit of the condition (1), it is advantageous for designing acompact lens system but is undesirable since it aggravates negativedistortion at the wide position and spherical aberration when an objectto be photographed is located at a short distance at the tele position.If f₁ exceeds the upper limit of the condition (1), in contrast, it willbe impossible to design a compact lens system and coma will beaggravated if a compact lens system dared to be designed with a firstlens group having such a long focal length.

In the second place, the lens system according to the present inventionis also characterized in that its second lens group has a focal lengthf₂ as defined in the condition (2). If f₂ is shorter than the lowerlimit of the condition (2), Petzval's sum will be large, curvature offield will be aggravated, spherical aberration will be unbalancedbetween the wide position and tele position, and zonal sphericalaberration will be aggravated. If f₂ exceeds the upper limit of thecondition (2), offaxial rays will be remarkably undercorrected thoughPetzval's sum will be small. Further, it is necessary to select a longtotal length D₂ of the second lens group as defined in the condition (3)in order to correct curvature of field and distortion favorably. Thecondition (3) further serves, in combination with the condition (2)already described above, for positively applying the concept ofenhancing performance and designing more compact lens systems forgeneral photographic cameras. The condition (3) makes it possible toselect relatively small radii of curvature on the surfaces of therespective lens elements which is effective for favorably correctingaberrations. If D₂ is shorter than the lower limit of the condition (3),Petzval's sum will be increased, spherical aberration will be aggravatedand negative distortion will not be corrected at the wide position. IfD₂ exceeds the upper limit of the condition (3), in contrast, thereoccurs tendencies to overcorrect spherical aberration in conjunctionwith composition of the third lens group, and to increase total lengthof the entire lens system.

Finally, when the first and second lens groups are so composed as tosatisfy the above-mentioned conditions (1), (2) and (3), the third lensgroup must comprises at least a positive meniscus lens element and acemented lens component. Said positive meniscus lens element in thethird lens group is required for correcting spherical aberration andcoma with good balance. In addition, said cemented lens component shouldpreferably be relatively thick and have a low refractive power. In orderto favorably correct chromatic aberration and astigmatism, it will beeffective to select thickness d₁₃ +d₁₄ of said cemented lens componentand its focal length f' so that they will satisfy the conditionsenumerated hereunder:

    0.25f<d.sub.13 +d.sub.14 <0.55f                            (4)

    |f'|>5f                                  (5)

As is easily understood from the embodiments illustrated, a stop can beset at a rather optional position in the zoom lens system according tothe present invention. When a stop is set on the object side, i.e., inthe second lens group, it will be possible to design a lens systemhaving a small outside diameter. When a stop is positioned at on theimage side, in contrast, coma will be corrected rather easily though itis disadvantageous for designing a compact lens system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 through FIG. 4 show sectional views illustrating the compositionsof the Embodiments 1 through 4 respectively of the present invention;

FIG. 5 through FIG. 7 show curves illustrating the aberrationcharacteristics of the Embodiment 1;

FIG. 8 through FIG. 10 show graphs illustrating the aberrationcharacteristics of the Embodiment 2;

FIG. 11 through FIG. 13 illustrate graphs showing the aberrationcharacteristics of the Embodiment 3; and

FIG. 14 through FIG. 16 show graphs illustrating aberrationcharacteristics of the Embodiment 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, some preferred embodiments of the present invention will bedescribed detailedly below:

    ______________________________________                                        Embodiment 1                                                                  ______________________________________                                           f = 1.0 ˜ 1.589                                                      r.sub.1 = 5.2540                                                                 d.sub.1 = 0.0815                                                                            n.sub.1 = 1.72342                                                                         ν.sub.1 = 38.0                                r.sub.2 = 1.1981                                                                 d.sub.2 = 0.3014                                                           r.sub.3 = -64.0574                                                               d.sub.3 = 0.1935                                                                            n.sub.2 = 1.80518                                                                         ν.sub.2 = 25.4                                r.sub.4 = -1.7706                                                                d.sub.4 = 0.0611                                                                            n.sub.3 = 1.51118                                                                         ν.sub.3 = 51.0                                r.sub.5 = 2.1700                                                                 d.sub.5 = 1.2580 ˜ 0.2649                                            r.sub.6 = 4.3124                                                                 d.sub.6 = 0.0815                                                                            n.sub.4 = 1.72                                                                            ν.sub.4 = 42.1                                r.sub.7 = 1.2007                                                                 d.sub.7 = 0.4016                                                                            n.sub.5 = 1.6485                                                                          ν.sub.5  = 45.8                               r.sub.8 = -1.4631                                                                d.sub.8 = 0.0766                                                           r.sub.9 = 1.1928                                                                 d.sub.9 = 0.0652                                                                            n.sub.6 = 1.72342                                                                         ν.sub.6 = 38.0                                r.sub.10 = 0.6313                                                                d.sub.10 = 0.0288 ˜ 0.0912                                           r.sub.11 = 0.6403                                                                d.sub.11 = 0.0978                                                                           n.sub.7 = 1.804                                                                           ν.sub.7 = 46.6                                r.sub.12 = 3.7617                                                                d.sub.12 = 0.0570                                                          r.sub.13 = 0.8881                                                                d.sub.13 = 0.0468                                                                           n.sub.8 = 1.744                                                                           ν.sub.8 = 44.7                                r.sub.14 = 0.5475                                                                d.sub.14 = 0.4244                                                                           n.sub.9 = 1.67003                                                                         ν.sub.9 = 47.3                                r.sub.15 = 0.8106                                                                d.sub.15 = 0.0815                                                          r.sub.16 = 3.7634                                                                d.sub.16 = 0.0615                                                                           n.sub.10 = 1.78472                                                                        ν.sub.10 = 25.7                               r.sub.17 = 0.8420                                                                d.sub.17 = 0.0619                                                          r.sub.18 = 3.9741                                                                d.sub.18 = 0.0823                                                                           n.sub.11 = 1.58921                                                                        ν.sub.11 = 41.1                               r.sub.19 = 1.5948                                                                f.sub.1 = -1.7813 -   f.sub.2 = 11.8158                                       f.sub.3 = 1.3883                                                           ______________________________________                                    

    ______________________________________                                        Embodiment 2                                                                  ______________________________________                                           f = 1.0 ˜ 1.587                                                      r.sub.1 = 5.6713                                                                 d.sub.1 = 0.0814                                                                            n.sub.1 = 1.72                                                                             υ.sub.1 = 42.1                          r.sub.2 = 1.1523                                                                 d.sub.2 = 0.3255                                                           r.sub.3 = -24.6163                                                               d.sub.3 = 0.1546                                                                            n.sub.2 = 1.80518                                                                          ν.sub.2 = 25.4                               r.sub.4 = -2.0972                                                                d'.sub.3 = 0.0081                                                          r'.sub.4 = -2.2618                                                               d.sub.4 = 0.0610                                                                            n.sub.3 = 1.50137                                                                          ν.sub.3 = 56.4                               r.sub.5 = 2.7085                                                                 d.sub.5 = 1.3174 ˜ 0.3328                                            r.sub.6 = 3.2343                                                                 d.sub.6 = 0.0814                                                                            n.sub.4 = 1.72                                                                             ν.sub.4 = 42.1                               r.sub.7 = 0.7385                                                                 d.sub.7 =  0.3836                                                                           n.sub.5 = 1.6485                                                                           ν.sub.5 = 45.8                               r.sub.8 = -1.4136                                                                d.sub.8 = 0.0765                                                           r.sub.9 = 1.3889                                                                 d.sub.9 = 0.0651                                                                            n.sub.6 = 1.72342                                                                          ν.sub.6 = 38.0                               r.sub.10 = 0.6610                                                                d.sub.10 = 0.0237 ˜ 0.0786                                           r.sub.11 = 0.6548                                                                d.sub.11 = 0.1111                                                                           n.sub.7 = 1.804                                                                            ν.sub.7 = 46.6                               r.sub.12 = 7.0504                                                                d.sub.12 = 0.0598                                                          r.sub.13 = -0.9411                                                               d.sub.13 = 0.0468                                                                           n.sub.8 = 1.744                                                                            ν.sub.8 = 44.7                               r.sub.14 = 0.8609                                                                d.sub.14 = 0.3999                                                                           n.sub.9 = 1.66998                                                                          ν.sub.9 = 39.3                               r.sub.15 = -0.9236                                                               d.sub.15 = 0.0500                                                          r.sub.16 = 6.3609                                                                 d.sub.16 = 0.0614                                                                          n.sub.10 = 1.78472                                                                         ν.sub.10 = 25.7                              r.sub.17 = 0.8373                                                                d.sub.17 = 0.0618                                                          r.sub.18 = -48.3564                                                              d.sub.18 = 0.0822                                                                           n.sub.11 = 1.58913                                                                         ν.sub.11 = 61.1                              r.sub.19 = -1.0554                                                               f.sub.1 = -1.7791                                                             f.sub.2 = 11.8013                                                             f.sub.3 = 1.3873                                                           ______________________________________                                    

    ______________________________________                                        Embodiment 3                                                                  ______________________________________                                           f = 1.0 ˜ 1.458                                                      r.sub.1 = 2.4225                                                                 d.sub.1 = 0.0816                                                                            n.sub.1 = 1.713                                                                            ν.sub.1 = 53.9                               r.sub.2 = 1.1551                                                                 d.sub.2 = 0.4082                                                           r.sub.3 = -33.2515                                                               d.sub.3 = 0.2041                                                                            n.sub.2 = 1.80518                                                                          ν.sub.2 = 25.4                               r.sub.4 = -2.6202                                                                d.sub.4 = 0.0612                                                                            n.sub.3 = 1.50137                                                                          ν.sub.3 = 56.4                               r.sub.5 = 1.4239                                                                 d.sub.5 = 1.1889 ˜ 0.4151                                            r.sub.6 = 2.6396                                                                 d.sub.6 = 0.4412                                                                            n.sub.4 = 1.68893                                                                          ν.sub.4 = 31.1                               r.sub.7 = 0.9257                                                                 d.sub.7 = 0.3633                                                                            n.sub.5 = 1.6516                                                                           ν.sub.5 = 58.7                               r.sub.8 =  -1.8282                                                               d.sub.8 = 0.0041                                                           r.sub.9 = 1.4003                                                                 d.sub.9 = 0.0657                                                                            n.sub.6 = 1.72342                                                                          ν.sub.6 = 38.0                               r.sub.10 = 0.6641                                                                d.sub.10 = 0.0378 ˜ 0.0901                                           r.sub.11 = 0.6873                                                                d.sub.11 = 0.1102                                                                           n.sub.7 = 1.7859                                                                           ν.sub.7 = 44.1                               r.sub.12 = 6.3436                                                                d.sub.12 = 0.1224                                                          r.sub.13 = -0.8140                                                               d.sub.13 = 0.0506                                                                           n.sub.8 = 1.72                                                                             ν.sub.8 = 43.7                               r.sub.14 = 0.7542                                                                d.sub.14 = 0.2600                                                                           n.sub.9 = 1.66998                                                                          ν.sub.9 = 39.3                               r.sub.15 = -0.8544                                                               d.sub.15 = 0.0531                                                          r.sub.16 = 2.1073                                                                d.sub.16 = 0.0612                                                                           n.sub.10 = 1.78472                                                                         ν.sub.10 =  25.7                             r.sub.17 = 0.8296                                                                d.sub.17 = 0.0694                                                          r.sub.18 = -6.8119                                                               d.sub.18 = 0.0816                                                                           n.sub.11 = 1.58913                                                                         ν.sub.11 = 61.1                              r.sub.19 = 1.0722                                                                f.sub.1 = -1.6220                                                             f.sub.2 = 13.3478                                                             f.sub.3 = 1.3030                                                           ______________________________________                                    

    ______________________________________                                        Embodiment 4                                                                  ______________________________________                                           f = 1.0 ˜ 1.456                                                      r.sub.1 = 2.7119                                                                 d.sub.1 = 0.0817                                                                            n.sub.1 = 1.713                                                                            ν.sub.1 = 53.9                               r.sub.2 = 1.2463                                                                 d.sub.2 = 0.3876                                                           r.sub.3 = -37.0068                                                               d.sub.3 = 0.2185                                                                            n.sub.2 = 1.80518                                                                          ν.sub.2 = 25.4                               r.sub.4 = -2.6686                                                                d.sub.4 = 0.0613                                                                            n.sub.3 = 1.50137                                                                          ν.sub.3 = 56.4                               r.sub.5 = 1.3744                                                                 d.sub.5 = 1.1828 ˜ 0.4084                                            r.sub.6 = 3.0705                                                                 d.sub.6 = 0.4624                                                                            n.sub.4 = 1.68893                                                                          ν.sub.4 = 31.1                               r.sub.7 = 0.9025                                                                 d.sub.7 = 0.3640                                                                            n.sub.5 = 1.6516                                                                           ν.sub.5 = 58.7                               r.sub.8 =  -1.6293                                                               d.sub.8 = 0.0041                                                           r.sub.9 = 1.3059                                                                 d.sub.9 = 0.0874                                                                            n.sub.6 = 1.72342                                                                          ν.sub.6 = 38.0                               r.sub.10 = 0.6312                                                                d.sub.10 = 0.322 ˜ 0.0846                                            r.sub.11 = 0.6471                                                                d.sub.11 = 0.1144                                                                           n.sub.7 = 1.7859                                                                           ν.sub.7 = 44.1                               r.sub.12 = 3.6198                                                                d.sub.12 = 0.0609                                                          r.sub.13 = -1.0349                                                               d.sub.13 = 0.0408                                                                           n.sub.8 = 1.697                                                                            ν.sub.8 = 48.5                               r.sub.14 = 1.8342                                                                d.sub.14 = 0.2749                                                                           n.sub.9 = 1.64769                                                                          ν.sub.9 = 33.8                               r.sub.15 = -1.2644                                                               d.sub.15 = 0.1156                                                          r.sub.16 = 4.3007                                                                d.sub.16 = 0.0613                                                                           n.sub.10 = 1.78472                                                                         ν.sub.10 =  25.7                             r.sub.17 = 0.9236                                                                d.sub.17 = 0.0613                                                          r.sub.18 = -10.0803                                                              d.sub.18 = 0.1021                                                                           n.sub.11 = 1.618                                                                           ν.sub.11 = 63.38                             r.sub.19 = -0.8906                                                               f.sub.1 = -1.6232                                                             f.sub.2 = 13.3582                                                             f.sub.3 = 1.3062                                                           ______________________________________                                    

wherein the reference symbols r₁ through r₁₉ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₁₈ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ throughn₁₁ denote refractive indices of the respective lens elements, thereference symbols ν₁ through ν₁₁ represent Abbe's numbers of therespective lens elements, the reference symbols f₁ through f₃ designatefocal lengths of the first, second and third lens groups respectivelyand the reference symbol f denotes focal length of the lens system as awhole which is expressed taking the focal length at the wide position as1.

Of the embodiments described above, Embodiment 1 is a lens system whichhas the composition shown in FIG. 1 and comprises a first lens groupconsisting of a negative meniscus lens element and a cemented lenscomponent, the aberration characteristics of said lens system beingillustrated in FIG. 5 (in case of f=1.6), FIG. 6 (in case of f=1.3) andFIG. 7 (in case of f=1). The Embodiment 2 has the composition shown inFIG. 2 and comprises a first lens group consisting of a negativemeniscus lens element and a positive and negative lens element which areseparated, radii of curvature on the object side surface of saidnegative element being represented by r'₄ and the airspace between theseparated lens elements is designated by d'₃ in the embodiment. Theaberration characteristics of the Embodiment 2 are illustrated in FIG. 8(f=1.6), FIG. 9 (f=1.3) and FIG. 10 (f=1). Further, the Embodiments 3and 4 have the compositions shown in FIG .3 and FIG. 4 respectively andcommonly comprise a first lens group in which the image side lenscomponent is a cemented doublet. The aberration characteristics of theseembodiments are illustrated in FIG. 11 through FIG. 13 (f=1.6, f=1.3 andf=1.0) and FIG. 14 through FIG. 16 (f=1.6, f=1.3 and f=1.0)respectively.

As is understood from the foregoing descriptions and embodimentsillustrated above, the present invention provides a very compactwide-angle zoom lens system wherein aberrations are favorably correctedin spite of a wide field angle of 84° at its wide position, and theEmbodiments 1 and 2 are epoch-making compact wide-angle zoom lenssystems which are usable with filters having a small diameter about 55mm.

I claim:
 1. A compact wide-angle zoom lens system comprising a firstlens group comprising a negative meniscus lens element having a concavesurface of the object side and a lens component having negativerefractive power, a second lens group comprising a positive cementeddoublet lens component and a negative meniscus lens element having aconvex surface on the object side and a third lens group comprising atleast a positive meniscus lens element having a convex surface on theobject side and a cemented doublet lens component, and said lens systembeing so designed as to change its focal length by displacing saidfirst, second and third lens groups respectively and, in addition, tomeet the following conditions:

    1.5f<|f.sub.1 |<2f, f.sub.1 <0           (1)

    12f<f.sub.2 <15f                                           (2)

    0.55f<D.sub.2 <f                                           (3)

wherein the reference symbols f represents the focal length of theentire lens system as a whole at its wide position, the referencesymbols f₁ and f₂ designate the focal lengths of the first and secondlens group respectively and the reference symbol D₂ denotes the totallength of the second lens group.
 2. A compact wide-angle zoom lenssystem according to claim 1 additionally satisfying the followingconditions:

    0.25f<d.sub.13 +d.sub.14 <0.55f                            (4)

    |f'|>5f                                  (5)

wherein the reference symbol d₁₃ +d₁₄ represents the thickness of thecemented components of the third lens group and the reference symbol f'designates the focal length of the cemented component of the third lensgroup.
 3. A compact wide-angle zoom lens system according to claim 1wherein the first lens group consists of a negative meniscus lenselement and a negative cemented doublet lens component.
 4. A compactwide-angle zoom lens system according to claim 3 wherein the third lensgroup consists of a positive meniscus lens element having a convexsurface on the object side, a cemented doublet lens component, anegative lens element and a positive lens element, and said lens systemhaving the following numerical data:

    ______________________________________                                           f = 1.0 ˜ 1.589                                                      r.sub.1 = 5.2540                                                                 d.sub.1 = 0.0815                                                                            n.sub.1 = 1.72342                                                                          ν.sub.1 = 38.0                               r.sub.2 = 1.1981                                                                 d.sub.2 = 0.3014                                                           r.sub.3 = -64.0574                                                               d.sub.3 = 0.1935                                                                            n.sub.2 = 1.80518                                                                          ν.sub.2 = 25.4                               r.sub.4 = -1.7706                                                                d.sub.4 = 0.0611                                                                            n.sub.3 = 1.51118                                                                          ν.sub.3 = 51.0                               r.sub.5 = 2.1700                                                                 d.sub.5 = 1.2580 ˜ 0.2649                                            r.sub.6 = 4.3124                                                                 d.sub.6 = 0.0815                                                                            n.sub.4 = 1.72                                                                             ν.sub.4 = 42.1                               r.sub.7 = 1.2007                                                                 d.sub.7 = 0.4016                                                                            n.sub.5 = 1.6485                                                                           ν.sub.5 = 45.8                               r.sub.8 = -1.4631                                                                 d.sub.8 = 0.0766                                                          r.sub.9 = 1.1928                                                                 d.sub.9 = 0.0652                                                                            n.sub.6 = 1.72342                                                                          ν.sub.6 = 38.0                               r.sub.10 = 0.6313                                                                d.sub.10 = 0.0288 ˜ 0.0912                                           r.sub.11 = 0.6403                                                                d.sub.11 = 0.0978                                                                           n.sub.7 = 1.804                                                                            ν.sub.7 = 46.6                               r.sub.12 = 3.7617                                                                d.sub.12 = 0.0570                                                          r.sub.13 = -0.8881                                                               d.sub.13 = 0.0468                                                                           n.sub.8 = 1.744                                                                            ν.sub.8 = 44.7                               r.sub.14 = 0.5475                                                                d.sub.14 = 0.4244                                                                           n.sub.9 = 1.67003                                                                          ν.sub.9 = 47.3                               r.sub.15 = -0.8106                                                               d.sub.15 = 0.0815                                                          r.sub.16 = 3.7634                                                                d.sub.16 = 0.0615                                                                           n.sub.10 = 1.78472                                                                         ν.sub.10 = 25.7                              r.sub.17 = 0.8420                                                                d.sub.17 = 0.0619                                                          r.sub.18 = 3.9741                                                                d.sub.18 = 0.0823                                                                           n.sub.11 = 1.58921                                                                         ν.sub.11 = 41.1                              r.sub.19 = -1.5948                                                               f.sub.1 = -1.7813                                                             f.sub.2 = 11.8158                                                             f.sub.3 = 1.3883                                                           ______________________________________                                    

wherein the reference symbols r₁ through r₁₉ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₁₈ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ throughn₁₁ denote refractive indices of the respective lens elements, thereference symbols ν₁ through ν₁₁ represent Abbe's numbers of therespective lens elements, the reference symbols f₁ through f₃ designatefocal lengths of the first, second and third lens groups respectivelyand the reference symbol f denotes focal length of the lens system as awhole which is expressed taking the focal length at the wide positionas
 1. 5. A compact wide-angle zoom lens system according to claim 1wherein the first lens group consists of a negative meniscus lenselement having a convex surface on the object side, a positive lenselement and a negative lens element.
 6. A compact wide-angle zoom lenssystem according to claim 5 wherein the third lens group consists of apositive meniscus lens element having a convex surface on the objectside, a cemented doublet lens component, a negative lens element and apositive lens element, and said lens system having the followingnumerical data:

    ______________________________________                                           f = 1.0 ˜ 1.587                                                      r.sub.1 = 5.6713                                                                 d.sub.1 = 0.0814                                                                            n.sub.1 = 1.72                                                                             ν.sub.1 = 42.1                               r.sub.2 = 1.1523                                                                 d.sub.2 = 0.3255                                                           r.sub.3 = -24.6163                                                               d.sub.3 = 0.1546                                                                            n.sub.2 = 1.80518                                                                          ν.sub.2 =25.4                                r.sub.4 = -2.0972                                                                d'.sub.3 = 0.0081                                                          r'.sub.4 = -2.2618                                                               d.sub.4 = 0.0610                                                                            n.sub.3 = 1.50137                                                                          ν.sub.3 = 56.4                               r.sub.5 = 2.7085                                                                 d.sub.5 = 1.3174 ˜ 0.3328                                            r.sub.6 = 3.2343                                                                 d.sub.6 = 0.0814                                                                            n.sub.4 = 1.72                                                                             ν.sub.4 = 42.1                               r.sub.7 = 0.7385                                                                 d.sub.7 = 0.3836                                                                            n.sub.5 = 1.6485                                                                           ν.sub.5 = 45.8                               r.sub.8 = -1.4136                                                                d.sub.8 = 0.0765                                                           r.sub.9 = 1.3889                                                                 d.sub.9 = 0.0651                                                                            n.sub.6 = 1.72342                                                                          ν.sub.6 = 38.0                               r.sub.10 = 0.6610                                                                d.sub.10 = 0.237 ˜ 0.0786                                            r.sub.11 = 0.6548                                                                d.sub.11 = 0.1111                                                                           n.sub.7 = 1.804                                                                            ν.sub.7 = 46.6                               r.sub.12 = 7.0504                                                                d.sub.12 = 0.0598                                                          r.sub.13 = -0.9411                                                               d.sub.13 = 0.0468                                                                           n.sub.8 = 1.744                                                                            ν.sub.8 = 44.7                               r.sub.14 = 0.8609                                                                d.sub.14 = 0.3999                                                                           n.sub.9 = 1.66998                                                                          ν.sub.9 = 39.3                               r.sub.15 = -0.9236                                                               d.sub.15 = 0.0500                                                          r.sub.16 = 6.3609                                                                d.sub.16 = 0.0614                                                                           n.sub. 10 = 1.78472                                                                        ν.sub.10 = 25.7                              r.sub.17 = 0.8373                                                                d.sub.17 = 0.0618                                                          r.sub.18 = -48.3564                                                              d.sub.18 = 0.0822                                                                           n.sub.11 = 1.58913                                                                         ν.sub.11 = 61.1                              r.sub.19 = -1.0554                                                               f.sub.1 = -1.7791                                                             f.sub.2 = 11.8013                                                             f.sub.3 = 1.3873                                                           ______________________________________                                    

wherein the reference symbols r₁ through r₁₉ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₁₈ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ throughn₁₁ denote refractive indices of the respective lens elements, thereference symbols ν₁ through ν₁₁ represent Abbe's numbers of therespective lens elements, the reference symbols f₁ through f₃ designatefocal lengths of the first, second and third lens groups respectivelyand the reference symbol f denotes focal length of the lens system as awhole which is expressed taking the focal length at the wide positionas
 1. 7. A compact wide-angle zoom lens system according to claim 3wherein the third lens group consists of a positive meniscus lenselement having a convex surface on the object side, a cemented doubletlens component, a negative lens element and a positive lens element, andsaid lens system having the following numerical data:

    ______________________________________                                           f = 1.0 ˜ 1.458                                                      r.sub.1 = 2.4225                                                                 d.sub.1 = 0.0816                                                                            n.sub.1 = 1.713                                                                            ν.sub.1 = 53.9                               r.sub.2 = 1.1551                                                                 d.sub.2 = 0.4082                                                           r.sub.3 = -33.2515                                                               d.sub.3 = 0.2041                                                                            n.sub.2 = 1.80518                                                                          ν.sub.2 = 25.4                               r.sub.4 = -2.6202                                                                d.sub.4 = 0.0612                                                                            n.sub.3 = 1.50137                                                                          ν.sub.3 = 56.4                               r.sub.5 = 1.4239                                                                 d.sub.5 = 1.1889 ˜ 0.4151                                            r.sub.6 = 2.6396                                                                 d.sub.6 = 0.4412                                                                            n.sub.4 = 1.68893                                                                          ν.sub.4 = 31.1                               r.sub.7 = 0.9257                                                                 d.sub.7 = 0.3633                                                                            n.sub.5 = 1.6516                                                                           ν.sub.5 = 58.7                               r.sub.8 = -1.8282                                                                 d.sub.8 = 0.0041                                                          r.sub.9 = 1.4003                                                                 d.sub.9 = 0.0657                                                                            n.sub.6 = 1.72342                                                                          ν.sub.6 = 38.0                               r.sub.10 = 0.6641                                                                d.sub.10 = 0.0378 ˜ 0.0901                                           r.sub.11 = 0.6873                                                                d.sub.11 = 0.1102                                                                           n.sub.7 = 1.7859                                                                           ν.sub.7 = 44.1                               r.sub.12 = 6.3436                                                                d.sub.12 = 0.1224                                                          r.sub.13 = -0.8140                                                               d.sub.13 = 0.0506                                                                           n.sub.8 = 1.72                                                                             ν.sub.8 =43.7                                r.sub.14 = 0.7542                                                                d.sub.14 = 0.2600                                                                           n.sub.9 = 1.66998                                                                          ν.sub.9 = 39.3                               r.sub.15 = -0.8544                                                               d.sub.15 = 0.0531                                                          r.sub.16 = 2.1073                                                                d.sub.16 = 0.0612                                                                           n.sub.10 = 1.78472                                                                         ν.sub.10 =25.7                               r.sub.17 = 0.8296                                                                d.sub. 17 = 0.0694                                                         r.sub.18 = -6.8119                                                               d.sub.18 = 0.0816                                                                           n.sub.11 = 1.58913                                                                         ν.sub.11 = 61.1                              r.sub.19 = -1.0722                                                               f.sub.1 = -1.6220                                                             f.sub.2 = 13.3478                                                             f.sub.3 = 1.3030                                                           ______________________________________                                    

wherein the reference symbols r₁ through r₁₉ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₁₈ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ throughn₁₁ denote refractive indices of the respective lens elements, thereference symbols ν₁ through ν₁₁ represent Abbe's numbers of therespective lens elements, the reference symbols f₁ through f₃ designatefocal lengths of the first, second and third lens groups respectivelyand the reference symbol f denotes focal length of the lens system as awhole which is expressed taking the focal length at the wide positionas
 1. 8. A compact wide-angle zoom lens system according to claim 3wherein the third lens group consists of a positive meniscus lenselement having a convex surface on the object side, a cemented doubletlens component, a negative lens element and a positive lens element, andsaid lens system having the following numerical data:

    ______________________________________                                           f = 1.0 ˜ 1.456                                                      r.sub.1 = 2.7119                                                                 d.sub.1 = 0.0817                                                                            n.sub.1 = 1.713                                                                            ν.sub.1 = 53.9                               r.sub.2 = 1.2463                                                                 d.sub.2 = 0.3876                                                           r.sub.3 = -37.0068                                                               d.sub.3 = 0.2185                                                                            n.sub.2 = 1.80518                                                                          ν.sub.2 = 25.4                               r.sub.4 = -2.6686                                                                d.sub.4 = 0.0613                                                                            n.sub.3 = 1.50137                                                                          ν.sub.3 = 56.4                               r.sub.5 = 1.3744                                                                 d.sub.5 = 1.1828 ˜ 0.4084                                            r.sub.6 = 3.0705                                                                 d.sub.6 = 0.4624                                                                            n.sub.4 = 1.68893                                                                          ν.sub.4 = 31.1                               r.sub.7 = 0.9025                                                                 d.sub.7 = 0.3640                                                                            n.sub.5 = 1.6516                                                                           ν.sub.5 = 58.7                               r.sub.8 = -1.6293                                                                 d.sub.8 = 0.0041                                                          r.sub.9 = 1.3059                                                                 d.sub.9 = 0.0874                                                                            n.sub.6 = 1.72342                                                                          ν.sub.6 = 38.0                               r.sub.10 = 0.6312                                                                d.sub.10 = 0.0322 ˜ 0.0846                                           r.sub.11 = 0.6471                                                                d.sub.11 = 0.1144                                                                           n.sub.7 = 1.7859                                                                           ν.sub.7 = 44.1                               r.sub.12 = 3.6198                                                                d.sub.12 = 0.0609                                                          r.sub.13 = -1.0349                                                               d.sub.13 = 0.0408                                                                           n.sub.8 = 1.697                                                                            ν.sub.8 = 48.5                               r.sub.14 = 1.8342                                                                d.sub.14 = 0.2749                                                                           n.sub.9 = 1.64769                                                                          ν.sub.9 = 33.8                               r.sub.15 = -1.2644                                                               d.sub.15 = 0.1156                                                          r.sub.16 = 4.3007                                                                d.sub.16 = 0.0613                                                                           n.sub.10 = 1.78472                                                                         ν.sub.10 = 25.7                              r.sub.17 = 0.9236                                                                d.sub.17 = 0.0613                                                          r.sub.18 = -10.0803                                                              d.sub.18 = 0.1021                                                                           n.sub.11 = 1.618                                                                           ν.sub.11 = 63.38                             r.sub.19 = -0.8906                                                               f.sub.1 = -1.6232                                                             f.sub.2 = 13.3582                                                             f.sub.3 = 1.3062                                                           ______________________________________                                    

wherein the reference symbols r₁ through r₁₉ represent radii ofcurvature on the surfaces of the respective lens elements, the referencesymbols d₁ through d₁₈ designate thicknesses of the respective lenselements and airspaces therebetween, the reference symbols n₁ throughn₁₁ denote refractive indices of the respective lens elements, thereference symbols ν₁ through ν₁₁ represent Abbe's numbers of therespective lens elements, the reference symbols f₁ through f₃ designatefocal lengths of the first, second and third lens groups respectivelyand the reference symbol f denotes focal length of the lens system as awhole which is expressed taking the focal length at the wide position as1.